The invention relates to an immediately acting digital-to-analogue converter.
Existing digital-to-analogue converters operate with a conversion time in the order of several hundred nanoseconds due to the existence of analogue circuits, designed to restore the converted analogue voltage by integration.
Solutions have been proposed as a means of reducing this conversion time and consist in reducing the integration capacities. However, these solutions have a limited effect because a reduction of this type is at odds with the very principle of the mode by which these systems operate.
The objective of the present invention is to remedy the disadvantages and limitations of known digital-to-analogue converters by using a digital-to-analogue converter which acts immediately, the response time being no longer than the cumulative switching time of linear amplifier circuit modules.
Another objective of the present invention is to operate an automatically programmable digital-to-analogue converter in which the automatic programming process is directly driven by the digital value to be converted to an analogue value.
The immediately acting digital-to-analogue converter proposed by the present invention enables a digital value to be to be converted, encoded on N bits, to be converted into an analogue voltage with a value ranging between an electric supply voltage Vcc and a reference voltage, being the ground voltage.
It is remarkable in that it comprises at least programmable circuits generating an image electric current proportional to the sum of the active values of electric voltages in a series of N electric voltages constituting a geometric progression of 2 and forming an analogue image of the weight of the bits between the most significant bit and the least significant bit on which the digital value to be converted is coded, the active values corresponding to the values for which the analogue image of the weight of the bits of the digital value to be converted correspond to a bit with a value of 1.
It also comprises first programmable corrector circuits receiving the image electric current and enabling a first programmed, corrected analogue voltage to be generated, proportional to the difference between the supply voltage Vcc and the weighted sum of the active values of electric voltages in the series of electric voltages, the weighting term of the weighted sum being inversely proportional to the number of bits of value 1 of the digital value to be converted, and second corrector circuits receiving the first programmed, corrected analogue voltage and enabling a second programmed, corrected analogue voltage to be generated, substantially equal in value and sign to the weighted sum of the active values of electric voltages in the series of electric voltages.
Finally, it comprises third corrector circuits, receiving the second programmed, corrected analogue voltage and enabling a programmed gain to be applied, equal to the inverse of the weighting term, which enables the analogue voltage between the supply voltage and the reference voltage to be generated, this value being equal to the sum of the active values of electric voltages in the series of electric voltages.
The immediately acting digital-to-analogue converter proposed by the invention finds applications in any field of high-speed electronics such as aeronautical or space electronics, for example for converting audio and/or video digital signals.